DE1809859A1 - Method and device for hardening straight glass panes - Google Patents

Description

LIBBEY-OWENS-PORD COMPANY 811 Madison Avenue, Toledo, Ohio, U. S, A.

Method and device for hardening straight glass panes

For this registration, the priority of the corresponding one will be given USA registration Ser. No. 683 581 of November 16, 1967 in Availed.

The invention relates to an improved method and device for the production of straight hardened Panes or sheets of glass.

With the known commercial processes for hardening or Tempering of glass panes or sheets, the panes are initially down to a substantially the softening point of the glass and then heated by quenching the pane to a temperature below the The temperature in the cooling area of the glass is hardened or toughened. Usually the heated disc is made out The furnace is placed on a series of horizontally arranged rollers that hold the disk between the upper and lower die heads propose the opposite

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! laughing the disc with currents from a suitable coolant, for example from air under a predetermined pressure, brush to quench the glass and to give him the necessary tension. When hardening γόη flat glass panes with a hen thickness of 6 ^ 35 mm the cooling air is at a relatively low pressure of, for example, 127 mm water column against the opposing ones Directed surfaces of the disc. This method has been used for hardening flat glass panes of 6 "55 mm Thickness proved to be completely satisfactory, it is at Hardening of thinner disks of, for example, 3 "175 mm Thickness, their need for different fields of application however, j does not continuously increase for a mass suction ■ economically feasible.

It is known to the person skilled in the art that with a decrease in the glass panes to be hardened, the cooling rate of the pane from the elevated temperature to below the temperature lying in the cooling area of the gas total -., igert \ must be grounded to produce a given hardness. However, it has been found that thin sheets of glass by simply increasing the air pressure directed against the glass sheet according to the aforementioned method Harden or prestress in a satisfactory manner.

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One of the difficulties and deficiencies encountered when using increased air pressure is that the disc at their movement on the conveyor rollers is subjected to a considerable "flutter", which maintains the required Makes flatness of the disc impossible and leads to excessive breakage losses. It appears on the At first sight, as if this difficulty could be remedied by putting the pressure of the air on top of the Slice is simply increased enough to hold the slice down on the conveyor rollers. However is this is not the case and this only makes the problem more difficult, since as a result of this difference you can see in the air pressure directed against the disc surfaces Curvature of the disc results.

The object underlying the invention is accordingly in the creation of an "improved" method and apparatus for hardening or toughening thin disks made of flat glass when moving forward along a predetermined horizontal movement can also be seen at which the flatness of the pane of glass; -, is preserved and the Breakage losses of glass on eir. Reduced minimum size be, v, ä '.: re.d £ le ic · Lr.ei tig ir. of the finished glass? · .Tibe the guaranteed-th shock-failure pattern is reached.

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.. ./4 BAD ORIGINAL

This is achieved according to the invention in that the pressure the cooling air directed against the underside of the glass panes is higher than that exerted on their upper sides Pressure, and that a supporting, counter-holding volume of air is built up over the glass panes to "increase the pressure." balance against the undersides of the discs and keep the disc in the predetermined path of movement.

Another feature of the invention is that the cooling air flows above and below the movement path the panes of glass are divided into a plurality of separate groups in such a way that by preventing the Mixing of the cooling air from these groups before they come into contact with the disc creates a swirl or turbulence to a large extent is avoided.

The invention is explained in more detail below with reference to the accompanying drawings. Show it*

Fig. 1 is a vertical longitudinal section through an inventive built system for hardening or toughening flat glass panes,

Fig. 2 is a vertical longitudinal section through a part the quenching zone,

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BAD ORiQlNAL

fig. 3 shows a plan view of part of one of the hardening blow heads ,

Pig. 4 shows a vertical partial section through part of one of the hardening die heads,

5 shows a section through the quenching zone along line 5-5 in FIG. 1, in the direction of the arrows,

6 shows a horizontal section along the line 6-6 in FIG. 5, in the direction of the arrows,

7 is a detailed view showing one of the throttle valves associated with the upper blow head;

Fig. 8 shows a conveyor roller of the quenching zone in cross section and

a schematic view of the conveyor system for the glass sheets.

According to the invention, a method for hardening or toughening flat glass panes is proposed

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in which a pane is held in a substantially horizontal position for its movement along a predetermined movement path through a heating zone in which the pane is heated to substantially the softening point of the glass, by a quenching zone and by a cooling zone arranged along the movement path, and at As the disc passes through the quenching zone, a large number of individual coolant flows, which are arranged at a short distance from one another in the longitudinal as well as in the transverse direction of the movement _{path, are directed under relatively high pressure perpendicularly against the opposing surfaces of the disc} , which is characterized in that the Coolant is supplied against the underside of the disk with a higher pressure than the coolant directed against its upper side and thus a volume of supporting, counter-holding coolant is built up over the disk in order to compensate for the increased pressure against the underside of the disk and the Sc keep in motion.

According to the invention, a device for implementation is also provided of the process in proposal, which consists of an upper and a lower overpressure chamber with each an inward-facing wall, from a multitude of

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tubular parts carried by each wall and communicating with the respective overpressure chamber, which extend perpendicularly in the direction of the movement path from both the upper and the lower wall and are arranged at their inner ends at a small distance apart from each other, from a A plurality of between the closely spaced inner ends of the upper and the Lower tubular parts arranged conveyor rollers for transporting a between the tubular parts to hardened or tempered heated glass sheet, the tubular parts for hardening or tempering the Glass pane against its opposite surfaces a large number of individual, but at a small distance can direct separate coolant flows, the pressure of which is directed against the underside of the disc directed coolant flows is higher than the pressure of the coolant directed against their upper side, and from the Upper overpressure chamber associated, the escape of the coolant inhibiting Drosselvorriohtungen, which is a for Adequate compensation of the higher pressure against the bottom of the disc and the disc on the roller conveyor holding volumei. from stutnondem, counter-holding] Build up coolant.

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BATH ORIGINAL

In the drawings, and particularly in Fig. 1, there is an apparatus for tempering or toughening a flat sheet of glass or a sequence of glass panes according to the invention. This system consists of a roller conveyor system A, a heating furnace B, one in close proximity to the output end of the furnace for receiving the heated Glass panes from the furnace arranged hardening or quenching zone C and a cooling zone adjoining zone C. D.

The furnace B consists of a substantially closed heating chamber 10, which is surrounded by a front wall 11, side walls 12, a rear wall 15 »a ceiling 14 and a floor 15 is delimited. To be hardened ~ planar glass panes 16 are along a substantially horizontal movement path through the heating chamber with the aid of a roller conveyor system A carried through that in the entrance and in the central area of the heating chamber 10 from a series of roles 17 exists. The heating chamber 10 is arranged under the conveyor rollers 17 in the side walls 12 with the aid of Burners 18 and kept at precisely regulated temperatures with the aid of corresponding burners 19 in the ceiling 14. the Burners 18 and 19 are preferably arranged and controlled so that from the input end to the output end of the Furnace's heat zones of gradually increasing temperatures arise. 9Q9826 / 10CU

As they pass through the heating chamber 10, the glass panes 16 are gradually heated from room temperature to the softening point of the glass at which all stresses in the glass are relieved. The motion & eschwindigkeit of the glass sheets is controlled in the course of each phase of operation so that it communicates with the during this phase at the S _c Heibe operation carried out in line. As a result, the speed of movement of the wafers is varied throughout the process so that they pass through the furnace B, at a speed from the furnace to the quenching zone C at a higher speed to avoid heat loss, through the quenching zone at a lower speed Use of relatively small equipment to enable it to be moved from the quench zone into cooling zone D at a higher speed and then through the cooling zone again at a lower speed.

The disks 16 are placed on rollers 20 of the conveyor system A as they approach the exit end of the furnace recorded by a power source21 with changeable Speed from a drive chain 23 together with the Rollers 22 of the entrance area of the quenching zone C are driven. When the heated glass sheets 16 the exit end reach the oven, they move through a

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slot-shaped opening 24 in the rear wall 13 and are added to a number of conveyor rollers 22 in the entrance area of the quenching zone C, whereupon they are on the Move conveyor rollers 25 further in the exit area of the quenching zone C. The rollers 25 are matched with rollers 26 in the entrance area of the cooling zone D from a power source 27 with variable speed via a drive chain 28 driven together. The glass panes would pass through the device at selected speeds moved through, which are consistent with the desired periods of time in which they move from a zone to the others, for example from furnace B into quenching zone C and from zone 0 into cooling zone D, are moved and are relatively slow or faster.

Thus, while the conveyor rollers 17 in the entrance and central area of the furnace B with the help of a not shown Power source are driven at a constant linear speed of about 5 m / min, the rollers 20 in the Near the exit end of the furnace and the rollers 22 in the entrance area of the quenching zone 0 alternating with 5 or 25 m / min. Be in a corresponding manner the conveyor rollers 25 removing the glass panes 16 from the quenching zone C and the rollers 26 in the entrance area

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the cooling zone D alternates with one of the desired high Speed, i.e. approx. 25 m / min, comparable speed and driven at a reduced speed which is equal to the speed of approx. 5 m / min is, with which the conveyor rollers 29 in the remaining cooling zone D are driven.

When transporting the glass panes through the system are to be hardened or toughened flat glass panes in the entrance end of the Htizkammer 10 on the Conveyor rollers 17 abandoned and as they wander through the oven B gradually to the softening point of the glass heated. As shown in Figures 1 and 9 of the drawing, each subsequent disc will as it approaches added to the exit end of the heating chamber 10 on the conveyor rollers 20, with the leading edge of the disc to Gegebner Time the beam e of a power source 21 actuating photoelectric cell E interrupts to the speed to increase the conveyor rollers 20 and 22 and the forward speed of the disc from approx. 5 m / min to approx. 25 m / min, so that the disc is swiftly carried into the quench zone 10 with a minimum loss of heat and between the upper one and the lower die 30 and 31, respectively will.

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As soon as the glass pane is actually between the opposing blow heads 30 and 31 in the Abschrekczone C is, interrupts'die front edge of the disk the light beam f / a second cell F, which the Power source 21 actuated again to set the conveyor speed of the rollers 20 and 22 and the forward speed of the disc to about 5 m / min as the disc moves through zone C and towards it this point in time at the same speed revolving conveyor roller η 25 is added.

When the glass sheet reaches the exit end of the quenching zone G, it breaks. Leading edge the light beam g a third cell D, through the power source 27, the speed of the clusters 25 and 26 and thus the forward speed to increase the disc to about 25 m / min, and to move the disk between the lower and upper blow heads 34 and 35 rapidly into the cooling zone D, wherein in the cooling zone D the temperature of the disc is gradually lowered. Finally interrupts as soon as the Disk is actually received between the blow heads 34 and 35, its leading edge the light beam h one fourth cell H to the speed of the power source 27, with which the rollers 25 and 26 are driven to decrease, so that the disc forwards on the rollers 29 and through the rest of the cooling zone at a speed of

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about 5 m / min is moved through, which corresponds to the speed, with which the rollers 29 are driven.

In general, the length of the blow heads 30 and 31 and the different speeds at which move the glass sheets into, through and out of quench zone C, so in relation to one another be brought that discs with a nominal thickness of 3f175 mm to achieve the desired hardening at least remain in the quenching zone for 4.5 seconds.

The upper and lower blow heads 30 and 31 in the quench zone C are of tubular construction and are supported by components 36 and 37, respectively. Each blow head consists of an overpressure chamber 38, which consists of a housing with a continuous side wall 39, an outer wall 40 provided with an air inlet 41 and one for the path of movement
Glass panes arranged in parallel and at one another
Side wall 39 formed continuous puddle 43
inner locking wall 42 attached by means of bolts or other suitable fastening means 44.

The closure wall 42 of each blow head is like I ¹ Ig. 3
shows, with a variety of regularly arranged and

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Provided at a small distance from each other separated openings 45, the with in the closure wall 42 fastened tubes stay in contact. The tubes 46 extend from the closure wall 42 perpendicularly in the direction of the Movement path of the glass panes. As Fig. 4 shows, are the ends of the tubes 46 received in the openings 45 and welded to the closure wall 42 or otherwise in appropriately attached to it. The tubes 46 are arranged offset from one another in numerous longitudinal and transverse rows. When passing through the glass panes between the blow heads 30 and 31 are both in the longitudinal and in Transverse direction of the pane against individual cooling air flows the opposing surfaces of the disc are directed to allow rapid cooling of the disc for hardening or To achieve toughening of the glass.

As discussed above, toughening or toughening thin sheets of glass must have a nominal thickness of, for example 3.175 mm of the coolant, usually consisting of air, at a relatively high pressure, i.e. greater than 508 mm WS, against the opposing disc surfaces. However, it turned out that a satisfactory hardening of the disc cannot be achieved if both side surfaces with the same

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Pressure can be applied. This is due to the fact that the disk heats up as it travels through the furnace picks up from the conveyor rollers, with the result that the underside of the disc when leaving the furnace a has a higher temperature than its top. Therefore, this temperature difference must to achieve a uniform Hardening of the disc surfaces in the quenching zone can be compensated for. In order to achieve this, against the Bottom of the disk Air is directed at a relatively higher pressure than against its top. It has been found that the pressure of the air directed against the top of the disc is preferably 762 to 889 mm WS and the pressure directed against the underside of the disc depending on The temperature difference between the surfaces of the disk when it emerges from the furnace is 889 to 1016 mm WS got to. Two typical examples are illustrated below:

Example I. Temperature

Disc top 595 ° C. Disc bottom 627 ° C

Air pressure

Disc top side 762 mm WS Disc bottom side 940 mm WS

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- 16 Example II

Temperature air pressure

Disc top side 607 ° C Disc top side 858 mm WS Underside of pane 612, 5 ° C underside of pane 889 mm WS

In each of the preceding examples, the tubes 46 were in forty-eight transverse rows of twenty-three tubes each arranged. The tubes in each transverse and longitudinal row were arranged at a center distance of 38 * 1 mm from one another ;, ■ while the mutually offset pipes are at a center distance of 25f8 mm were arranged. The tubes were 254 mm long, had an inner diameter of 10.32 mm and were: with their inner ends spaced apart by 28.6 mm from the sheets of glass advancing on the conveyor.

In addition, it was found that in the above-described tubular hardening device, the use There is a higher pressure against the underside of the disc than against its upper side in connection with the counter pressure the air in the lower die, is a serious disadvantage in that it is due to the thinness of the disk

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a decided need of the disc to rattle on the There is conveyor rollers, so that the flatness of the disc is adversely affected and excessive Result in breakage losses. If the pressure difference is too great, the disc has a tendency to move away from the conveyor rollers take off and with the ears of the upper BJ, askopfes to get in touch.

In order to remedy this deficiency, means are provided according to the invention provided in order to accumulate a relatively large volume of supporting, counter-holding air above the glass pane, that is enough to hold the disc down on the conveyor rollers, but not for further hardening or toughening of the glass is used. As a result, there are on opposite sides of the upper die 30 baffle or throttle flaps 47 and 48 are provided, which with their upper end 49 to the closure wall 42 of the Hinged overpressure chamber and with the help of a rod hinged at one end to the throttle valve at 51 50 are adjustable, which protrudes through an opening of the angled end 52 of the holder 53 and is screwed onto it Nuts 54 is provided so that the damper or throttle flap about the pivot point 49 or Swivel outwards and lock in the desired position leaves.

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The throttle valves 47 and 48 extend over the entire Length of the blow head and lie in their in Pig, 5 vertical position shown flat and level against the pipes, so that they the air outlet to each other restrict opposite sides of the die. In other words, the throttle valves are used for delimitation the air between the pipes, so that there is a relatively large volume of supporting, Build up and maintain counter-holding air sufficient to hold the higher pressure against the underside of the Balance the disc and hold the disc down on the conveyor rollers.

It has also been found that the expulsion of air from the tubes 46 at relatively high pressures There is a lot of turbulence in the blow heads, which is sufficient to lift the disks off the conveyor rollers by blowing them and "pushing them up" between the blow heads. To avoid this, the pipes are made with the help of baffles 55 made of metal inc. Divided into a variety of groups. As in Pig. 1 shown, these baffles extend transversely to the path of movement of the glass pane., With their inner ends on the respective closure wall 42 of the overpressure chamber welded or otherwise in a suitable manner

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attached to it. The tubes are preferably divided into groups of four rows each. The baffles 55 of the upper and lower blow heads are also preferably arranged in an aligned position with one another and protrude slightly beyond the pipes. The task of the baffles is to act as modulators to reduce the Influence constantly changing air turbulence in the To serve blowheads. For example, the air escapes if there is no glass between the blow heads, on the way with the least resistance. Upon entering With a pane of glass between the blow heads, the pane of glass acts like a barrier to normal airflow messes up quite violently and creates harmful air turbulence between the pipes. However four rows of tubes are separated from the adjacent rows of tubes by using the baffle plates 55, so that in this way a mixing of the air between adjacent groups with the resulting resulting air turbulence is reduced to a minimum will.

It is known that when hardening or toughening glass panes by brushing the heated panes with Flowing or jetting a coolant such as

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Air, the surfaces of the S _c Heibe placed under compressive stress. This takes place within seconds, so that the back pressure or back pressure of the air retained between the tubes of the upper and lower blow head does not affect the hardness or pretension of the glass.

Because the quenching zone C is relatively close to the exit end of the furnace B, it is important to take precautions to prevent the cooled air from entering is backed up from the blow heads into the furnace, which would lead to a decrease in temperature in the furnace which would require an increase in the normal gas pressure would make to maintain the required oven temperatures.

For this purpose, the air shields are in front of and immediately adjacent to the upper and lower blow heads 30 and 31, respectively 56 and 57 are provided, each consisting of a horizontally arranged distribution line 58 with a the path of movement of the glass pane directed and close to it adjoining, relatively narrow outlet hlitz 59 pass. Each distribution line is on one or provided with an inlet opening 60 at both ends,

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to which a compressed air source can be connected. In the The air brought in by the distributor lines is discharged from them between the blow heads, whereby the pressure of the Air is such that the air back pressure through the outlet opening 24 in the rear wall 30 into the 02en B and is reduced to a minimum. Metal shields 61 and that serve as an additional barrier against air backflow into the furnace. The shields 56 and 57 have a second important task, which consists in allowing the glass panes to enter the gush of air formed between the blow heads.

The roles of the entire conveyor system A are opposite to one another Ends in bearings 63 and 64 supported on the sides of the device, as shown in FIG. 5, by supports 65 and 66 or in any other suitable manner. Rolls 22 and 25 in quench zone C. are of a special design in order to better distribute the air directed against the underside of the glass panes and also to keep the glass panes in a straight path as they move on the conveyor rollers. For this purpose, each of these rollers consists of a metal shaft 67, which is connected to a suitable belt 68 from a non-rubbing material or scratching material, e.g.

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Fiberglass or asbestos, is wrapped. The belt 68 is from one end to the other of the shaft 67 in one of FIG. 5 apparent mutual distance between the individual turns of the tape helically wound around them. The tape is wound on adjacent rollers in opposite directions to avoid any inclination the panes of glass to prevent a transverse change. The helix is preferably wound so that the surface contact between the belt and the roller shaft is around 35 #. Wrapping the conveyor rollers with tape reduces the contact area between the rollers and the panes of glass, while the distance between the individual turns of the tape recess areas are created leaves, which allow a more even distribution of the cooling air under the panes. In the absence of these recess areas, the cooling air would be adjacent between each other Conveyor rollers are limited and cause the thin panes of glass to bulge.

The hardened or toughened glass panes are when leaving the quenching zone C in the cooling zone D between one or more pairs of upper and lower blow heads 34 and 35, respectively. With the help of these blow heads are on the opposite faces

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the hardened glass panes in a known manner cooling air flows directed to continue cooling of the wafers. The illustrated blow heads 34 and 35 are with each other provided separately arranged ribs 69 and 70, which extend transversely to the path of movement of the discs and are provided with exit slots 71 and 72 to rest against the opposing surfaces of the between them direct long, narrow air currents through the discs. The degree of cooling of the glass panes is determined by the Controlled air pressure by exerting different air pressures on the top and bottom of the disc will. As the hardened glass panes pass through the cooling zone, the air is relatively low Pressure of, for example, 50.8 to 127 mm WS applied to the opposing surfaces of the disc. However, the pressure of the air on the top of the disk must be sufficiently higher than that on its underside exerted pressure in order to keep the disc lightly pressed onto the Förderrolleη without lifting it off.

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Claims (13)

Claims 1. Process for hardening or toughening flat glass panes, in which a disk is moved along a predetermined path through a heating zone in which the disk heated until substantially the softening point of the glass, through a quench zone and along one the movement path arranged cooling zone in substantially is held in a horizontal position, and as they pass through the quenching zone, a large number of individual pieces separated from each other at a small distance from each other both in the longitudinal and in the transverse direction of the movement path Coolant flows under relatively high pressure perpendicularly against the opposing surfaces of the Disc is straightened, characterized in that that the coolant is supplied against the underside of the disc with a higher pressure than the coolant directed against its upper side, and that above the disk a volume of supporting, counter-holding Coolant is built up to compensate for the increased pressure against the underside of the disc and the To keep the disc on the track. 909826/1OiH 2. The method according to claim 1, characterized in that in the entrance end of the quenching zone (G) above and below the path of movement of the glass pane (16) is introduced under pressure to prevent an escape of To prevent coolant from entering the quench zone. 3. The method according to claim 1 or 2, characterized in that the volume of supporting, counter-holding coolant The amount of coolant escaping from it is controlled via the glass pane (16) by regulating it. 4. The method according to claim 1 to 5, characterized in that that the coolant flows above and below the movement path of the glass pane (16) in a plurality of Groups are divided to reduce air turbulence. 5. The method according to any one of claims 1 to 4, characterized by that the disks (16) are conveyed through the quenching zone (C) on several separate transverse support lines will. 6. Apparatus for performing the method according to claim 1 to 5, consisting of an upper and a lower ... / 26 909826 / 100A Overpressure chamber, each with an inward-facing wall, a plurality of tubulars carried by each wall and communicating with the respective hyperbaric chamber Parts that extend perpendicularly in the direction of the path of movement from both the upper and the lower wall extend and are arranged separated from each other at their inner ends at a small distance a plurality of arranged between the ends of the upper and lower tubular parts conveyor rollerη for Transporting a heated sheet of glass to be hardened or tempered between the tubular parts, wherein the tubular parts for hardening or toughening the glass sheet against its opposing surfaces direct a large number of individual, but at a short distance from each other separate coolant flows, from where the pressure of the coolant flows directed against the underside of the disc is higher than the pressure of the against its upper side directed coolant, and from the upper overpressure chamber (38) associated, the escape of the coolant from her inhibiting throttle devices (47,48), which are used to compensate for the increased pressure sufficient volume against the underside of the disc (16) and holding the disc on the roller conveyor (25) Build up supporting, counter-holding coolant. .. ./27 909826/1004 18098 7. Apparatus according to claim 6, characterized in that the throttle device from adjustable, for Eegelung there is throttle valve (47, 48) serving the escaping coolant quantity. 8. Apparatus according to claim 6 or 7, characterized by Devices for dividing the tubular parts (46) into various groups to reduce air turbulence. 9. Apparatus according to claim 8, characterized in that the devices from a plurality of to the conveyor rollers (25) parallel arranged vertical baffles or guide plates (55) exist. 10. The device according to claim 9 »characterized in that the upper and lower tubular parts (46) in Groups dividing baffles or guide plates (55) are arranged in an aligned position with one another and on their inner ends protrude beyond the tubular parts (46). 11. Device according to one of claims 6 to 10, characterized in that at the front end of the overpressure chamber (38) air shields (56, 57) are arranged, which under .. ./28 909826/1004 Direct air under pressure between the overpressure chambers above below the conveyor rollers (25) _? to inhibit the escape of coolant » 12 ₀ - Device according to one of Claims 6 to 11, characterized in that each of the conveyor rollers consists of a shaft (6?) And a coating (68) for the shaft made of non-frictional material, the coating (68) being ρ separately from one another the disc (16) has contacting parts and recess areas left between them for the horizontal passage of cooling air between the shaft (67) and the disc (16) ₀ 13. The apparatus according to claim 12 _9, characterized in that the coating consists of a band (68) which is helically wound around the shaft (67) _? - that separate turns are created, the tapes being wound in opposite directions on the shafts (67) of adjacent rolls * Patent attorneys Seiler and Pfem / h? 909826/1004 Blank page